Fun with NULL

I think this is interesting:

SELECT * FROM dual WHERE (1 BETWEEN 0 AND NULL)     -- FALSE
SELECT * FROM dual WHERE (0 BETWEEN 1 AND NULL)     -- FALSE
SELECT * FROM dual WHERE NOT (1 BETWEEN 0 AND NULL) -- FALSE
SELECT * FROM dual WHERE NOT (0 BETWEEN 1 AND NULL) -- TRUE

This has a good explanation however I am still embarrassed :)